Grace Hopper

Hopper wrote the first compiler, a program that translates human readable instructions into machine code, in 1952, arguing at a time when most programmers wrote directly in machine instructions that computers could be made to understand something closer to English. Her compiler work led to FLOW-MATIC and then to COBOL, a business programming language designed to be readable by non specialists, which she championed through the 1960s. She served in the United States Navy for over four decades and retired as a rear admiral, the oldest serving officer in the Navy at the time. She is also credited with popularizing the term debugging after removing a moth from a relay in the Harvard Mark II computer in 1947, though the word itself predates that incident.